In the present specification, the term of media represents, for example, paper moneys, checks, tickets, and certificates. The media have a thinner thickness than a width or a length thereof, and exist in various forms. In the present specification, the paper moneys will be described as an example of the media.
In general, a paper money discrimination apparatus is applied to an automatic teller machine, a medium handler, or an automatic vending machine to recognize a magnetic component, images, watermarks, fluorescent inks, and a variety of figures and characters printed on a paper money and to find out the type of the paper money and discriminate if the paper money is genuine or counterfeit.
FIG. 1 is a sectional view partially showing the paper money discrimination apparatus to read a magnetic component printed on the paper money.
Referring to FIG. 1, first and second magnetic sensors 12a and 12b are arranged in line with each other in an upper bracket 10 while being spaced apart from each other at a predetermined distance, thereby detecting a magnetic component printed on a paper money 30. In this case, sensing surfaces of the first and second magnetic sensors 12a and 12b are directed downward such that the sensing surfaces are exposed, and provided perpendicularly to a transfer direction of the paper money 30. Accordingly, the magnetic component printed on the paper money 30 is detected.
In this case, sensing surfaces of the first and second magnetic sensors 12a and 12b are directed downward to be exposed, and provided perpendicularly to a transfer direction of the paper money 30 so that the magnetic component printed on the paper money 30 can be detected.
The first and second magnetic sensors 12a and 12b are magnetoresistance sensors, that is, magnetic pattern recognition sensors.
Upper paper money feeding rollers 14a and 14b are provided in line with the first and second magnetic sensors 12a and 12b, and driven corresponding to lower paper money feeding rollers 24a and 24b to transfer the introduced paper money 30.
The lower paper money feeding rollers 24a and 24b to transfer the paper money 30 according to the rotation of a paper money feeding roller shaft 20, and sensor contact rollers 26a and 26b to make a magnetic component printed on the paper money 30 be more exactly detected by lifting the paper money 30, which is moving, to the first and second magnetic sensors 12a and 12b, so that the paper money 30 approximates the first and second magnetic sensors 12a and 12b, are provided in a lower bracket 20.
The rollers 24a, 24b, 26a, and 26b are arranged at a predetermined interval along the paper money feeding roller shaft 22 in such a manner that the lower paper money feeding rollers 24a and 24b face the upper paper money feeding rollers 14a and 14b, and the sensor contact rollers 26a and 26b face the first and second magnetic sensors 12a and 12b. 
Lower support springs 28a and 28b are provided at both ends of the paper money feeding roller shaft 22 to continuously push upward the paper money feeding roller shaft 22. Accordingly, spaces between the rollers 24a, 24b, 26a, and 26b and to the upper paper money feeding rollers 14a and 14b and the first and second magnetic sensors 12a and 12b respectively facing the rollers 24a, 24b, 26a, and 26b can be maintained closely. In this case, bearers 29a and 29b are provided to prevent the rollers 24a, 24b, 26a, and 26b from being excessively close to the upper paper money feeding rollers 14a and 14b and the first and second magnetic sensors 12a and 12b respectively due to the elasticity of the lower support springs 28a and 28b. 
Meanwhile, although not shown, the paper money discrimination apparatus comprises Amp & Band-pass Filters, which receive sensed analog signals for the magnetic component from the first and second magnetic sensors 12a and 12b, respectively, amplify the analog signals to signals having stable intensities, and filter noises amplified together with the amplification of the analog signals, an AD (Analog to Digital) converter, which coverts the two filtered analog signals into digital signals, and an MCU (Micro-Controller Unit) which reads the two converted digital signals to discriminate if the introduced paper money 30 is genuine or counterfeit.
In the paper money discrimination apparatus having the above structure, a paper money can be in closely contact with magnetic sensors by a roller that is elastically supported, so that the performance to discriminate between paper moneys can be improved.
The magnetic component detected by the first and second magnetic sensors 12a and 12b contains a noise component. The noise component is generated because the first and second magnetic sensors 12a and 12b are affected by a magnetic field generated due to the operation of an actuator (e.g., a motor or a solenoid) provided in the vicinity of the first and second magnetic sensors 12a and 12b. In addition, the noise component is generated because switching noise of an internal circuit (i.e., a power circuit) is introduced into the first and second magnetic sensors 12a and 12b. 
FIG. 2 shows a graph representing the output of two digital signals from the AD converter. An X axis of the graph represents a position value of a magnetic component and a Y axis of the graph represents an intensity value of the magnetic component.
As shown in FIG. 2, the digital signals converted by the AD converter contain both of a magnetic component A of the introduced paper money 30 and a magnetic component (i.e., noise; B) introduced from the internal circuit or the outside. The magnetic component A of the paper money 30 is sensed only by the first magnetic sensor 110a (see {circle around (a)}). This is because a magnetic component of each paper money is printed only on a specific position of the paper money. If the paper money 30 is reversely introduced, the magnetic component A printed on the paper money 30 may be sensed by the second magnetic sensor 12b (see {circle around (b)}).
However, the paper money discrimination apparatus has the following problems.
Since the noise B has a relatively large magnetic intensity value, when the MCU reads the magnetic component A of the paper money 30 to discriminate if the paper money is genuine or counterfeit, the noise B degrades the ability of the MCU to discriminate if the paper money is genuine or counterfeit.
In addition, since the MCU receives two digital signals (see {circle around (a)} and {circle around (b)}) from the AD converter and performs a predetermined operation with respect to both of the two digital signals, time to discriminate if the paper money is genuine or counterfeit is required as much as that of the operation.
Further, to prevent the noise B from being introduced from the internal circuit or the outside, a high-price magnetic shielding layer and non-magnetic material may be used. In this case, costs are additionally caused by the magnetic shielding layer and the non-magnetic material, so that the maintenance for the paper money discrimination apparatus may be difficult.